Greenwood



(No Model.) 4 Sheets-Sheet; 1.

J.-GREENWOOD. ELECTRODE FOR USE IN THE MANUFACTURE OF OHLORIN AND,

GAUSTIG SODA. No. 514,318,

Patented Feb. 6, 1894.

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J. GREENWOOD.

ELECTRODE FOR USE IN THE MANUFACTURE OF 0111.031 AND GAUSTIO SODA.

No. 514,318,. Patented Feb. 6,18%.

(No Mael. 4 Sheets Sheet a. J. GREENWOOD. ELECTRODE FOR USE IN THE MANUFACTURE OF GHLORIN AND GAUSTIG SODA.

Patented Feb. 6, 1894.

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(No Model.) 4 Shegtsr-Sheet 4;

. J. GREENWOOD. ELECTRODE FOR USE IN THE MANUFACTURE OF GHLORIN AND GAUSTIG SODA.

No. 514,318. Patented Feb. 6, 1894."

W i/lnesses Inventor.

UNITED STATES 'PATENT ()FFICE.

JAMES GREENWOOD, OF LONDON, ENGLAND, ASSIGNOR TO THE OAUSTIC SODA AND GHLORINE SYNDICATE, LIMITED, OF SAME PLACE.

ELECTRODE FOR USE IN THE MANUFACTURE OF CHLORIN AND CAUSTIC SODA.

SPECIFICATION forming-part of Letters Patent No. 514,318, dated February 6, 1894.

Original application filed January 10, 1893, Serial No. 388,012. Divided and this application filed October 18, 1892. Serial No- 449,282. (110 model. Patented in England February 5, 1891, No. 2,134; in Germany A ril 10, 1891, No 62,912: in France May 11, 1891, No. 213,377; in Norway May 13, 1891, No. 2,372: in Belgium May 15,1891, No. 94,903; in Cape of Good Hope June 5, 1891, No, 182; in Natal June 10,1891; in Victoria. June 1'7, 1891, No. 8,816; in South Australia June 19,1891, No. 1,959; in New South Wales June 20, 1891,110. 3,065; in Queensland June 22, 1891, No. 1,350; in Italy June 30, 1891,

' XXV, 29,711, and LV1II,359; inlortugal July 1, 1891,11'0- 1,596: in Turkey July 8, 1891,1l'm234; inSpain July 18,1891, No. 12,110; in Geylon September 14, 1891, 110.369; in India December 4,1891,N0.259: in Canada July 29, 1892, No. 39,524: in Austria-Hungary February 6, 1892, No, 41,706 and No. 77,721, and in Transvaal March 15, 1892, N0. 347.

'To all whom it may concern:

' 213,377, dated May 11, 1891; in Norway, No.

2,372, dated May 13, 1891; in Belgium, No. 94,903, dated May 15, 1891; in Cape of Good Hope, Reg. Fol. 689/182, dated June 5,1891; in Natal, dated J une 10, 1891; in Victoria, No. 8,816, dated June 17, 1891; in South Australia, No. 1,959, dated June 19, 1891; in New South Wales, No. 3,065, dated June 20, 1891; in Queensland, No. 1,350, dated June 22, 1891; in Italy, XXV, 29,711, and LVIII, 359, dated June 30, 1891; in Portugal, No. 1,596, dated July 1, 1891; in Turkey, No. 234, dated July 8, 1891; in Spain, No. 12,110, dated July 18, 1891; in Canada, No. 39,524, dated July 29, 1892; in Geylon,No. 369, dated September 14, 1891; in *India, No. 259, dated December 4, 1891; in Austria-Hungary, No. 41,706 and No. 77,721, dated February 6, 1892, and in Transvaal, No. 347, dated March 15,1892,) of which the following is a specification.

This invention relates to improvements in the manufacture or production of chlorine and caustic soda by means of electrolysis.

In manufacturing or producing caustic soda, and chlorine according to my invention, asolution of sodium chloride or common salt is decomposed by a current of electricity in one or a series of vessels of cylindrical, square, oblong, or other convenient or suitable form, made of iron or combined metal and carbon having porous partitions or diaphragms, all as more particularly hereinafter described by referenceto the accompanying drawings, in which- Figures 1 and 2 are respectively a vertical and a horizontal section of a vessel of circular form for producing caustic soda and chlorine gas according to this invention. Fig. 3 is an elevation showing three of the said vessels arranged in combination with suitable tanks and pumps for carrying out the process. Figs. 4 and 5 are respectively an elevation (partlyin section) and a plan with the cover removed of a vessel of an oblong form.

Similar reference letters indicate similar or corresponding parts throughout the drawings.

A circular form of vessel shown in Figs. 1 to 3 shall first be described.

a indicates the wall of the electrolytic vessel, which wall, when of copper, or other metal than iron, is coated within with carbon in the manner hereinafter described, the carbon being shown at b; but if the wall is of iron it is used uncoated. The wall of the vessel also serves as the cathode, the terminal a of which is connected withthe negative pole of a dynamo or other electrical generator. In the center of the said vessel, a combined metal and carbon cylinder d. is placed around a, metal core, in a vertical position, and. forms the anode, the terminal a. of which core is connected with the positive pole of the said dynamo or other electrical generator. This carbon cylinder is formed of several segments, each of which has a film of copper deposited on its inner surface,and to which surface the metal core can adhere. Thus the adhering surface is the surface which receives the deposit of copper to which the metal core adheres. For working on a large scale 'howover, I find that the plate form or type of anode, as shown in Fig. 4, is preferable to the cylinder type or form. It is the carbon that is required to be combined with the copper or other suitable metal. I find that typemetal is the most suitable in actual" practice. The metal-carbon combination referred to above, is formed by electrolytically depositing a film of copper or other suitable metal upon the adhering surface of the carbon, and then soldering the same tot-he copper or other metal required to be combined with it, thus forming a perfectly homogeneous combination of the metal and carbon, which is well adapted for electrodes in which metal is altogether unsuitable for the purpose. The anode d is insulated from the cathode a by means of a slate or other insulating plate f placed at the bottom of the vessel.

At a suitable distance between the anode d andthe'catbode a, a porous partition or diaphragm g divides the vessel into what may be described as the anode or chlorine section 71. and the cathode or caustic soda section 1'. The use of this diaphragm 9 enables the usual porous partition of high resistance hitherto employed to be entirely dispensed with. The diaphragm is preferably formed by a number of V-shaped troughsj of porcelain orother suitable substance such as glass or slate which are filled withcarded asbestus fiber or other suitable porous materialsuch as a quantity of powdered steatite. These troughs are built up inside each other, as shown clearly in Fig. vl, so asto preventthe diffusion of the chlorine gas evolved in the anode section It into the cathode section '5, thus separating the pro ducts obtained in each of the said sections in the most efiectual manner. Both the sections 72. and 11 are filled at the commencement with a solution of sodium chloride which is caused to flow into them at the bottom through the pipes Z and m, respectively, from .the supply tanks 0 and p. The solution will quickly circulate upward (whereby the polarization will be'reduced to a minimum) and will be decomposed by means of a current of electricity which is caused to pass through the same, whereby chlorine will be evolved in the anode section It and caustic soda will be formed in the cathode section 1'.

The flow of the solution can be regulated and maintained in a known, simple and automatic-manner such, for example, as by placing the supply-tanksoand p ata suitable'elevation, as shown in Fig. 3, and also by arranging the vessels so that the two solutions can flow through their respective sections in the entire series into delivery tanks q, 1'. From the said delivery tanks the solutions are pumped by suitable pumps, such as s, 15 back to the supply-tanks 0, 10 the circulation being maintained until the solutions are sufficiently decomposed and the caustic soda solution is of the strength required for any particular purpose, the solution of sodium chloride in the tank 19 being gradually changed to caustic soda.

Each electrolytic vessel is sealed by a porcelain or other suitable cover it, and pipes 21 are connected with the sections 71., h to conduct the chlorine gas away.

to, w are cocksfor drawing off the contents of the tanks 0 and p as required.

In the oblong form of vessel shown in Figs. 4 and 5, the electrolytic vessel is divided into a series of anode and cathode sections by the anodes and cathodes in the form of plates marked (1 and a respectively and extending, v

as also do the porous partitions g across the vessel between .the sides thereof. The cathodes which inthis'instance'do not form the walls of the vessel, are indicatedas not being carbon covered. The pipes land m are arranged so as to allowthe solutions to flow through their respective chambers. chlorine and caustic soda being produced and collected in a similar manner to that described with reference to Fig. .3.

The caustic soda solution produced by the method hereinbefore described contains a certain proportion of sodium chloride in solu- 'tion,and for some purposes it is found advantageous to eliminate such sodium chloride. This isaccomplished bytransferring the caustic alkaline liquor fromthe tank 19 to evaporating pans in which the liquor is concentrated until the sodium chloride is precipitatedandthe-caustic soda alone remains in solution. If, however, the caustic soda is required in the solid form the evaporation is continued to afurther stage until the residual liquor becomes so concentrated as to solidify on cooling and is then packed in the usual manner.

It will be understood from the preceding, that whether the anode be of the plate type, or of the cylinder type or form, there is a metal core extending through it, the carbons and the metal core forming a solid homogeneons plate or cylinder.

Having now particularly described the nature of the said invention and in what manner the same is to be performed, what I claim is A compound electrode composed of a body of carbon, a cavity or space extending into such body, an electro-deposited film of metal on the surface of such cavity, and a copper or other metal rod or plate soldered to said metallic film.

JAMES GREENWOOD. Witnesses:

G. I. REDFERN, A. ALBUTT.

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